Use of Field Data to Support European Water Framework Directive Quality Standards for Dissolved Metals

Abstract

Quality standards (QS) for dissolved metals in freshwaters have been proposed underthe European Water Framework Directive (WFD) and are based mainly upon laboratory ecotoxicity data. Uncertainties remain about laboratory-to-field extrapolation to establish QS that are neither over- nor underprotective. Freshwater benthic macroinvertebrates are a group of organisms of known sensitivity to heavy metals. We analyzed a dataset from England and Wales of dissolved metal concentrations (cadmium, chromium, copper, iron, nickel, lead, and zinc) and associated benthic invertebrate community metrics, using piecewise regression, quantile regression, and information on metal concentrations consistent with good quality status. Analysis of these field data suggests that dissolved metal QS proposed under the WFD are similar to metal concentrations in rivers associated with unimpaired benthic invertebrate assemblages in England and Wales. The only exceptions to this are QS for iron and zinc, where use of relatively large assessment factors leads to standards that are substantially below concentrations associated with impaired invertebrate assemblages in the field.

Revisions to the derivation of the Australian and New Zealand guidelines for toxicants in fresh and marine waters

“…van Dam et al (this issue) provide several examples about how this can be done, and also identify several recent methods that may be useful for using field data to derive trigger values. This is an area that is receiving increasing attention (e.g., Crane et al, 2007;Kwok et al, 2009).…”

Water quality guidelines for chemicals: learning lessons to deliver meaningful environmental metrics

“…Also, there is a need to account for additional pressures and confounding factors when considering field data (e.g. through the use of limiting functions, such as piece-wise or quantile regression; Crane et al 2007). The derivation, validation, and acceptance of WQGs is further complicated through the conundrum that WQGs are generally derived using laboratory toxicity tests by exposing a species or a group of species to a single chemical stressor, while in reality, various species in a community are simultaneously exposed to multiple toxicants and stressors (although often field-based data will reflect multiple exposures and stressors; Leung et al 2005;Peters et al 2011).…”

Preliminary assessment of total dissolved trace metal concentrations in Sava River water

“…The maximum allowable concentrations (MAC) were derived on the basis of the acute toxicity only for Cd and Hg, while the annual average (AA) values were defined for Cd, Hg, Pb and Ni. The AA values were also proposed for Cu, Zn and Fe in the unpublished draft UK reports (Crane et al, 2007). As a part of preliminary assessment of Sava River water quality status we have compared our data with the defined annual average levels, although the concentrations measured in this study refer to only one season.…”